In recent years, an image pickup apparatus has been available, such as a digital still camera that generates a picked-up image by picking up an image of a subject such as a person and records this generated picked-up image. Also, as this image pickup apparatus, to facilitate an image pickup operation by a user, an image pickup apparatus provided with an auto focus (AF: Auto Focus) function for automatically performing a focus (focus point, focal point) adjustment at the time of image pickup has been widely available.
For such an image pickup apparatus, for example, an image pickup apparatus that forms a pair of images by performing pupil division on light that passes through an image pickup lens and measures an interval between the formed images (detects a phase difference) to decide a position of the image pickup lens is proposed (for example, see PTL 1). This image pickup apparatus forms a pair of images by providing an image sensor with a pixel for focus detection where a pair of light receiving elements are provided to one pixel and calculates a shift amount of the focus by measuring an interval between the formed images. Then, this image pickup apparatus calculates a movement amount of the image pickup lens on the basis of the calculated shift amount of the focus and adjusts the position of the image pickup lens on the basis of the calculated movement amount to effect focusing (focus adjustment).
According to the above-mentioned conventional technology, as both pixels including the pixel for phase difference detection (focus detection) and the pixel for picked-up image generation are provided to one image sensor, it is not necessary to separately provide two sensors, i.e. a sensor for focus detection and a sensor for picked-up image.